In rendering a two-dimensional (2D) image of three-dimensional (3D) object(s), there may or may not be a background color or “clear color” remaining in some portions of the image following rendering. This varies depending on the kind of object(s) rendered, whether the object(s) fill the entire image and/or the purpose for which the object(s) are rendered. Thus, whether there will be pixels that remain uncolored during rendering such that they must be colored a clear color to make the image complete is often not known in advance.
Given this uncertainty, it has become accepted practice to initially color all pixels of an image with the clear color to ensure that no pixels are left with an undefined or random color after rendering. However, this invariably means that at least some, if not all, of the effort expended in first coloring of all of the pixels with the clear color is wasted, as at least some of them will be overwritten with a color of an object during rendering.
This waste is not just measurable in time wasted between uses of a rendering engine to render images while the writing of clear color values to all pixels is occurs, but is also measurable in wasted processor time and wasted memory bandwidth that could have been employed for other purposes than repeatedly writing the color data value for the clear color into memory locations for every pixel. It is with respect to these and other considerations that the embodiments described herein are needed.